Z axis with 1 stepper motor over belt

Hi there!

A common problem is that the z-axis with two motors can geht out of sync.
My idea is now to do it with one motor that drives the two z-axis lead screws with a belt.

What do you think of this? Has anyone tried this?

THX!

It has been done to a Prusa Mendel before, but I can't remember by who. The original Sells Mandel used a single motor and belt to drive the screws from below.

However, I think you might also consider a belt driven Z axis. The screws cause the famous wobble problem, and speed limitations. The downside to the purely belt drive system is that a way must be devised to keep the Z axis from falling when the power is removed from the steppers. Several interesting ideas are explored in the thread on Variant of Goopyplastic's Tantillus Variant (about halfway into page 2). One machine that implemented one of the ideas there used a worm gear reduction to increase lifting force and prevent the axis from falling.

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However, I think you might also consider a belt driven Z axis.

... and say good bye to any kind of layer thickness precision. Having something solid on the Z axis has a reason: this gear must withstand the acceleration forces of the print head which happen in vertical direction, too.

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Hi

I do not know if you understood me correctly
here is a picture - what I think:

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bensch
Has anyone tried this?

Have you ever looked at the orginal (Sells) Mendel?

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Traumflug

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However, I think you might also consider a belt driven Z axis.

... and say good bye to any kind of layer thickness precision. Having something solid on the Z axis has a reason: this gear must withstand the acceleration forces of the print head which happen in vertical direction, too.

Simply not true. I use a cable driven z and print at 0.08 a lot. The Ingentis has a belt Z and it prints at 0.1mm with as good or better precision then most lead screw Z axis machines. [plus.google.com] . The printxel has a belt Z axis and has such good layer consistency it lead me to make the cable Z. Up printers uses belt Z axis and inspired Printxel to use a belt z. I personally think it is the only way to go and would never even consider building another machine with a lead screw.

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My Prism uses belt-driven leadscrews and i'm perfectly happy with it. I never really saw the appeal of a dual motor z axis.

My printer (MegaMax) has two acme screws to lift the X-axis that are turned by a single belt/motor and it works perfectly. The only reason I can think of to use two motors instead of a belt with one motor is cost. Two motors are often cheaper (especially if one has access to surplus motors) than a closed loop belt and all the required pulleys (unless you can get those surplus). A big advantage to using a single drive belt is that if you want to move the X-axis up and down, you can just grab the belt and give it a pull. With two motors you better drive them electronically or you'll have to relevel the X-axis.